This invention relates generally to electronic oscillator circuits and more particularly to such oscillator circuits which may be "phase locked" and/or switched "on" and "off" by carriers optically generated in semiconductor elements of microwave solid state oscillators.
Many applications, such as radar systems having antenna arrays, for example, require phase coherency between a number of remotely located microwave subsystems. Such phase coherency has been generally implemented in present systems either by using a single microwave oscillator and dividing the output for distribution, or by phase locking separate oscillators by injection of a microwave reference signal. In accordance with either of these signal distribution techniques, microwave energy is routed to the remotely located subsystems by metal waveguides or coaxial cables which add undesirable weight to the system.
An article entitled "Illumination Improves Trapatt Performance" on page 14 of the January, 1977, issue of the magazine "Microwaves" relates to a scheme for using optical illumination to improve the performance of Trapatt oscillators. The article also suggests that by varying the optical illumination level, the Trapatt output frequency can be varied to obtain ultra-fast intrapulse frequency switching. By way of contrast, the subject invention uses modulated optical signals as the illuminating source and a solid state oscillator detects and interacts with the "dc" component and the modulation component of the optical signals to achieve switching and phase locking, respectively, of the oscillator.